Circularly Polarized Antenna For BDS

With the rapid development of wireless communication technology, global satellite navigation and positioning system has a high positioning accuracy, wide coverage, fast response, all weather operations and other advantages for its application in the field of military and civil more widely. Beidou satellite navigation system( BDS) is independently developed by China, has a short message function can be two-way exchange of information, has been rapidly developed in recent years. The Beidou satellite navigation antenna as a converter of BDS terminal and outside space, its performance directly determines the accuracy of the Beidou satellite navigation and positioning system. Terminal antenna of the satellite navigation system towards a low profile, compact and lightweight, compatible with a plurality of satellite navigation systems direction. Based on circularly polarized antenna microstrip, this paper studied and analyzed the methods of designing low-profile, small round BDS antenna.The first part summarizes the research review and current status of circularly polarized antenna, and then introduced the relevant basic theory and knowledge of microstrip circular polarization antenna, teh common methods to achieve circular polarization of microstrip antenna and the design principles of Wilkinson power divider are also introduced, and finally introduced Metasurface loading circle polarized antenna.Based on conventional double-fed Microstrip circularly polarized antenna, the second part designed a interference antenna array of BDS, which works at BDS B3 band and compatible with GPS. The antenna system with advantages of stable performance and low profile, was very ideal for maritime, aerospace field line.The third part, in order to make the antenna structure lightweight, simplistic. This paper gives two forms of circularly polarized antenna design methods,which are that,the circular polarization microstrip with gap and coplanar waveguide circularly polarized antenna. The two types of circularly polarized antennas do not need to use additional feed network, can reduce the cost of the antenna. But the antenna has a narrow bandwidth, Because of there is no metal under the coplanar waveguide circularly polarized antenna, It has certain limitations in practical applications.In order to overcome the disadvantages of Microstrip circularly polarized antenna with gap and CPW circularly polarized antenna of the third part, the forth part designedtwo linear polarization to circular polarization by the ultra-loading Metasurface circularly polarized antenna, Both antennas’ cross-section are only two 4mm, with good VSWR bandwidth and 3d B axial ratio bandwidth, also the simulation and test results are in good agreement.